docs: def merge(self, other):
          """Merge data from another Compound into this Compound."""
          log.debug('Merging: %s and %s' % (self.serialize(), other.serialize()))
          for k in self.keys():
              for new_item in other[k]:
                  if new_item not in self[k]:
                      self[k].append(new_item)
          log.debug('Result: %s' % self.serialize())
          return self